DeDent Andrea C, McAdow Molly, Schneewind Olaf
Department of Microbiology, University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
J Bacteriol. 2007 Jun;189(12):4473-84. doi: 10.1128/JB.00227-07. Epub 2007 Apr 6.
Surface proteins of Staphylococcus aureus fulfill many important roles during the pathogenesis of human infections and are anchored to the cell wall envelope by sortases. Although the chemical linkage of proteins to cell wall cross bridges is known, the mechanisms whereby polypeptides are distributed on the staphylococcal surface have not been revealed. We show here that protein A, the ligand of immunoglobulin, is unevenly distributed over the staphylococcal surface. Upon removal with trypsin, newly synthesized polypeptide is deposited at two to four discrete foci. During subsequent growth, protein A appears to be slowly distributed from these sites. When viewed through multiple focal planes by laser scanning microscopy, protein A foci are arranged in a circle surrounding the bacterial cell. This pattern of distribution requires the LPXTG sorting signal of protein A as well as sortase A, the transpeptidase that anchors polypeptides to cell wall cross bridges. A model is presented whereby protein A deposition at discrete sites coupled with cell wall synthesis enables distribution of protein A on the staphylococcal surface.
金黄色葡萄球菌的表面蛋白在人类感染的发病过程中发挥着许多重要作用，并通过分选酶锚定在细胞壁包膜上。尽管蛋白质与细胞壁交联桥的化学连接方式已知，但多肽在葡萄球菌表面的分布机制尚未揭示。我们在此表明，免疫球蛋白的配体A蛋白在葡萄球菌表面分布不均。用胰蛋白酶去除后，新合成的多肽沉积在两到四个离散的位点。在随后的生长过程中，A蛋白似乎从这些位点缓慢分布。通过激光扫描显微镜从多个焦平面观察时，A蛋白位点呈围绕细菌细胞的环状排列。这种分布模式需要A蛋白的LPXTG分选信号以及分选酶A，分选酶A是将多肽锚定到细胞壁交联桥的转肽酶。我们提出了一个模型，即A蛋白在离散位点的沉积与细胞壁合成相结合，使得A蛋白能够在葡萄球菌表面分布。
